The CORE Joist Stiffener Whole (JSW) is designed specifically for 45 × 240 mm joists. It reinforces
joists when service penetrations are required. With an integrated one-piece structure and a
central circular opening, it allows safe passage of pipes or ducts while restoring structural
integrity. Manufactured from 1.55 mm galvanised steel, the JSW is intended for use in internal
closed space applications (in accordance with NZS 3604:2011 Table 4.1).
Features & Benefits
- One-piece structure covers the penetration area and reinforces load capacity.
- Pre-formed fixing holes for convenient nail or screw installation.
- Central circular hole (Ø185 mm) suitable for common pipes and ducts.
- Designed to fit 45 × 240 mm standard joists.
- Made from 1.55 mm galvanised steel, strong and corrosion resistant.
- Quick installation with a single component.
Installation Criteria
- Fixing holes can be filled with nails or screws, but do not mix both.
- All pre-formed holes must be fully filled.
- Minimum end distance = joist depth (≥240 mm).
- Minimum edge distance = 40 mm (to prevent timber splitting and maintain structural
integrity).
- Timber around penetration zone must be free from defects such as knots, splits, or warping.
- Intended for internal closed space use only, not for outdoor or damp environments.
Installation Steps
- Mark the hole position on the joist (follow distance and depth requirements).
- Drill a hole of diameter ≤185 mm.
- Place the JSW stiffener over the penetration, ensuring snug fit with joist and flooring.
- Fix the stiffener using nails or screws through all pre-formed holes.
- Check installation for firm seating and secure fit.
